Gas tungsten arc welding (GTAW), also known as tungsten inert gas (TIG) welding, is an electrical welding process that uses the arc from a tungsten electrode to produce heat sufficient to create a plasma “puddle” to weld or fuse work pieces together. TIG welding can be used for a number of materials and alloys and is thus a very versatile welding process. However, the welding parameters and electrode sizes are often adjusted based upon the material being welded. For example, the diameter of the non-consumable tungsten electrode can vary between about 0.5 mm and about 6.4 mm (0.020 in.-0.25 in.) depending upon the workpiece material and type of weld, and the length of the electrodes can range from about 75 mm to about 610 mm (3 in.-24 in.).
The weld area is protected from atmospheric contamination by an inert shielding gas, such as argon. A welding power supply provides an electrical current that, upon creation of an arc between the electrode and the material being welded, produces concentrated thermal energy sufficient to weld the piece(s). The focused heat is sufficient to place the contact area, as well as an optional filler rod, into a plasma state. Air cooling systems are most often used for low-current operations, however water cooling is generally required within the torch head for a majority of TIG welding systems in order to dissipate heat in higher current applications or in applications requiring longer duty cycles.
Tungsten arc welding gas shielding torches employ dedicated collets and collet bodies for holding only one specific diameter electrode within the torch head. Electrode collets are typically made from copper in a tubular shape and have at least two longitudinal gaps or slots to allow the diameter of the collet to be radially compressed when moved in relationship to the interior conical shape of an adjacent collet body. This compression of the collet minimally reduces the opening therein to engage and secure the electrode within the nominal internal radial area of the collet. Since the collet is compressed against the electrode over a relatively small area, the current density per unit area is significant and substantial heat may be generated due to the electrically resistive connection to the electrode, which also may perpetuate peripheral arcing within the collet. Accordingly, the electrode, as well as the collet, has a tendency to erode over time due the effect of repetitive expanding and contracting caused by both the resistive and conducted heating and subsequent cooling. The situation is further aggravated due to the copper collet having a coefficient of thermal expansion of 9.8×10−6 in/in/° F., whereas the tungsten electrode only expands about half as much (3.9×10−6 in/in/° F.), thereby potentially causing a loose fitting electrode while welding, potentially further increasing the electrical resistance and/or causing the electrode to become unstable and to move within torch head.
Collets and collet bodies are provided in at least six aperture sizes to accommodate various diameters of the job specific electrode. Therefore a significant limitation of the existing collets is that each electrode size requires a specific corresponding collet and collet body. Consequently, each time an alternate electrode diameter is required, the collet assembly must be interchanged as well. For example, it is required to have on hand at least one 1/16 inch collet and collet body to accompany a 1/16 inch tungsten electrode, as well as a ⅛ inch collet and collet body for a ⅛ inch electrode, and so forth. This unfortunately becomes a logistical challenge, as well as a time consuming exercise each time the electrode is interchanged for another size. Moreover, the use of collets prevents the reversal of electrodes that may develop a bead or enlarged end.
When an electrode comes in direct contact with a work piece the tip becomes contaminated when “foreign” metal that is transferred and adheres to the tip of the tungsten electrode. This added material produces a mushrooming of the tip and requires the electrode to be either reground or replaced. The use of an adjustable electrode receiver as disclosed herein, however, provides a sufficient opening or adjustability for the mushroomed end of the electrode to be flipped, end for end, and reinserted as the enlarged and contaminated end is passed through the adjustable opening. Thus, it is a further objective to provide an electrode receiver that will allow insertion of the expanded/contaminated end therethrough, and thereby avoiding a problem with the use of sized collets to hold electrodes.
The internal metal parts of a torch are preferably made of copper or brass in order to conduct electrical current and transfer heat with minimal resistance across a relatively small contact area. The body of the torch is made of heat-resistant, insulating plastics and similar materials for both covering the metal components as well as providing insulation from heat and electricity to protect the welder. Additionally, provisions may be provided to allow a constant flow of the shielding gas to pass through the torch handle and electrode receiver to the work piece area in order to provide an inter gas atmosphere in proximity to the weld.
In the interest of versatility and convenience, a welder should be enabled to select and use any size electrode at anytime, to effect optimal welding, without the need to reconfigure the electrode receiver within the torch head. In other words the configuration of the torch head and associated housing should not dictate the size or shape of an electrode. Therefore, an adjustable electrode receiver, that can be varied as needed to accommodate a variety of different size electrodes, provides a distinct advantage when using an electric welding torch, such as the case with TIG welding.
The embodiments disclosed herein are directed to an improved torch with an adjustable or variable electrode receiver that eliminates the need for collets in order to enable use of a plurality of electrode sizes. In the improved torch a plurality of electrically conductive, adjustable wedges are employed to provide an adjustable electrode aperture through which electrodes of various sizes, and shapes, may be placed and held.
In accordance with one aspect of the disclosed embodiments, there is provided an electric arc welding torch having an adjustable electrode receiver, comprising: a plurality of radially positioned electrode securing wedges forming an aperture therebetween; an internal conical surface, each securing wedge traversing, in unison in a longitudinal direction to form a variable aperture therebetween; an electrode passing through said variable aperture in contact with each securing wedge, said securing wedges further providing electrical contact between the electrode and the conical surface; and an adjusting collar positioning the securing wedges longitudinally along the internal conical surface, said adjusting collar forcing said wedges into secure contact with the electrode, wherein the aperture is adjustable for use with a range of electrode diameters.
In accordance with another aspect of the disclosed embodiments, there is provided a method for using a welding torch in combination with an arc welder, comprising: providing an adjustable electrode receiver having a plurality of electrically conductive wedges defining an aperture therein, said aperture being suitable for receiving a plurality of electrodes of different diameters; inserting a first electrode into the aperture in the electrode receiver; adjusting the wedges to be in electrical contact with an outer surface of the first electrode; and securing the first electrode in a fixed position using the wedges by applying a force to said wedges via a threaded collar in contact with the first electrode.
In accordance with a further aspect of the disclosed embodiments, there is provided A welding system, comprising: a power supply; an inert gas supply; and a welding torch electrically connected to the power supply and coupled to the inert gas supply, said torch including an adjustable electrode receiver suitable for receiving a plurality of electrodes of different diameters.
Other and further objects, features and advantages will be evident from a reading of the following specification and by reference to the accompanying drawings forming a part thereof, wherein the examples of the presently preferred embodiments are given for the purposes of disclosure.
The various embodiments described herein are not intended to limit the invention to those embodiments described. On the contrary, the intent is to cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the welding torch and adjustable electrode receiver as defined by the appended claims.